Many parts of the world have inadequate rainfall at different times of the year sufficient to sustain non-native vegetation, such as lawns, playing fields, golf course, flowers, shrubs and other ground cover. Irrigation systems have been extensively developed that include a plurality of sprinklers connected to pressurized water supply lines and solenoid actuated valves. An electronic controller automatically turns the valves ON and OFF in accordance with the run and cycle times of a watering program to provide vegetation in different zones of the sprinkler system with the desired amount of precipitation. A wide variety of sprinklers have been developed for use in such systems, including drip, bubbler, impact drive, spray, rotary stream, and rotor type sprinklers.
Spray type sprinklers are well known in the irrigation art and typically include a spray nozzle that is screwed to the upper end of a fixed vertical riser or a telescoping vertical riser in the case of a so-called pop-up sprinkler. The spray nozzle is usually a generally cylindrical construction made of plastic parts. Typically a fixed orifice distributes water radially in a relatively thin fan-shaped pattern to close-in vegetation, e.g. turf and shrubs located seventeen feet or less from the spray nozzle. The size of the fixed orifice is chosen to provide, for example, one-quarter, one-half and full circle arc of coverage. The size of the fixed orifice can also be selected to deliver a particular flow rate in terms of gallons per minute, although arc size largely determines flow rate. Usually the fixed orifice is sized and configured to provide matched rates of precipitation over a given sector size. For example, a one-quarter circle arc spray nozzle will typically deliver water at half the rate of a one-half circle arc spray nozzle of the same design. Conventional spray nozzles often include a small throttling screw that can be turned with a screwdriver from the top side to adjust the flow rate of the sprinkler, which can also adjust the reach or radius to some degree. Examples of conventional irrigation spray nozzles are disclosed in U.S. Pat. Nos. 4,189,099; 4,739,934; 5,642,861; and 6,158,675. Some spray type sprinklers include an internal pressure regulator as disclosed in U.S. Pat. No. 5,779,148 for example. Some spray type sprinklers include an internal debris strainer or screen as disclosed in U.S. Pat. No. 4,913,352.
U.S. Pat. No. 4,579,285 granted Apr. 1, 1986 to Edwin J. Hunter and entitled ADJUSTABLE SPRINKLER SYSTEM discloses an irrigation spray nozzle with an adjustable arc spray orifice that can be adjusted from about zero degrees to three hundred and sixty degrees. One of two opposing spiral peripheral lips can be rotated relative to the other via a top screw to change the circumferential length of the nozzle orifice formed between the two lips. The height of the upper lip relative to the lower lip can also be adjusted with the same screw in order to change the flow rate for a preselected arc of coverage. This invention alleviates the necessity of manufacturing spray nozzles with different spray patterns and it has therefore enjoyed widespread commercial success, however, it is more expensive to manufacture than conventional fixed-arc irrigation spray nozzles.
Landscape maintenance personnel, gardeners, homeowners and the like often require the ability to inspect the nozzle from the top of the sprinklers to verify or determine whether the correct nozzle is installed. Most sprinklers are installed in a subterranean manner so that their upper ends are level with the surface of the ground or turf. Nozzle inspection is easiest when it is not necessary to manually pull up the riser to see any arc size or flow rate indicators. Color indications for nozzle radius and/or flow rate are common in the irrigation industry. The color is often in the base or inner part of the sprinkler, because customers do not like to have the complete nozzle colored, preferring a less apparent black top. A less visible color marking is acceptable to most customers and can be used to facilitate top-down visual inspection. Some sprinkler nozzles use an additional part that is colored and attached to the top of the nozzle. This is costly and the part can come off. Some sprinkler nozzles have a painted surface for color identification. This is also costly and the paint can wear off the nozzle.
A common way to indicate arc size on a spray nozzle is to mold a series of radially extending ridges on the top side of the outer ring of the nozzle which extend circumferentially the same distance as the arc of the spray pattern, e.g. one-half circle. However these ridges are tiny and are made of the same black plastic as the remainder of the nozzle and are therefore extremely difficult to observe from the top side of a pop-up sprinkler.
The water distribution pattern of an irrigation spray nozzle is conventionally produced with a hole in a lower inlet part and a peg from an upper nozzle part that enters the hole. The peg has details that allow flow through the hole and out of the nozzle. An upper deflector area above the peg opening controls the water distribution. The peg opening is usually a section of a round hole or notch. The control of the pattern using a deflection of the flow is not precise and produces spikes and voids along the intended edges.